The bond between carbon (C) and sulfur (S) is best classified as a polar covalent bond.
To understand why, we should look at the electronegativity values of both elements. Electronegativity is a measure of an atom’s ability to attract and hold onto electrons. Carbon has an electronegativity of about 2.55, while sulfur has an electronegativity of around 2.58. The difference in electronegativity between these two elements is minimal (approximately 0.03), indicating that neither atom exerts a significantly greater pull on the bonding electrons.
In general, if the difference in electronegativity between two atoms is less than 0.5, the bond is typically considered nonpolar covalent. A difference between 0.5 and 1.7 often results in a polar covalent bond, and differences greater than 1.7 generally indicate ionic bonding. Since the difference here is very small, we see that the bond has some degree of polarity, but is still largely covalent in nature. Therefore, we classify the bond as a polar covalent bond.